In 1904 Eugène Dubois published the first report on fossil mammals from the vicinity of Tegelen. After a century of research the clay-pits from the area are known as a classical locality for Villafranchian mammals. Antje Schreuder's work was particularly important for making the fossils from Tegelen known. Her papers, however, also indicate some problems. The large mammal fossils were gathered by clay-workers in the local ceramic industry, and the fragmentary nature of the fossils is partly caused by injudicious handling while extracting the bones from the clay. Because the Tegelen fossils are chance finds rather than the results of careful excavations, their exact provenance is not established. The only exception is the collection of micromammals, which was gathered by Thijs Freudenthal during expeditions in the 1970s. Large size variation in the cats and hyenas, and the presumed presence of Stephanorhinus kirchbergensis cast doubt on to whether the fossils from Tegelen represent a single time frame.